Getting married in Japan

I live in the US and proposed to my Japanese girlfriend last month in Japan and we plan on getting married around mid August in Japan, and I've been trying to find out as much information to make the process of this as easy as possible. Problem is none of it has made very good sense to me, or slightly different scenarios.
We've known each other for about 8 years, first meeting as she was my host student when I went to Japan, and she came to the US to stay with me 2 times since, and I've gone there 2 times since. So I think we've got plenty of proof of knowing each other.
The part I'm confused about is how/when do I apply for the Certificate of Eligibility, and the Spouse Visa? Am I able to apply for both of these while I'm there in Japan in August? Do I need to start the process here? Starting it here sounds like a nightmare trying to send mail back and forth to Japan from the US.
I will be going there on a tourist visa, and we plan on getting married within a few days of me arriving there.
Am I able to buy a one way airplane ticket? Or do I need to buy a round trip?
Can I get some step by step instructions on what I should be doing to help relieve my stress?

You need to think of two stages. (1) Getting married, then (2) applying for a Spouse of Japanese National resident status/visa.

(1) Since you plan to get married in Japan, that means according to the Japanese law; you can come on Temporary Visitor status (assuming you are a US citizen).

You might want to read this first (again I am assuming you are a US citizen):
https://jp.usembassy.gov/u-s-citizen-services/child-family-matters/mar...

(2) Then if you want to continue to stay and apply for change from your Temporary Visitor status to Spouse of Japanese National resident status. This will be an application for a change, not for a new visa, so you won't bother with certificate of eligibility. (That comes into play if you apply from outside Japan.)

Read here for Application for Change of Resident Status:
http://www.immi-moj.go.jp/english/tetuduki/kanri/shyorui/02.html

As long as you have all the documents ready and are able to complete the application procedure within the 90 days allowed under Temporary Visitor status, you should be able to continue to stay.

Thank you very much for your response! It's as simple as that?? I don't need a Certificate of Eligibility? Everywhere I've read makes it sound like it's the golden ticket. Is that because I'm a US citizen? I just need to go to the
Also, could I be denied entry if I fly there on a one way ticket? Should I tell customs my intent?

A bit old thread, but here Firas clearly explains "visa," "CoE," and "resident status."

https://www.japan-guide.com/forum/quereadisplay.html?0+156643

Just be sure to find out exactly what documents are needed to (1) get married, and to (2) apply for change of resident status, so that you can complete the procedure within the time allowed on your temporary visitor status.


About flight tickets: since you will be entering Japan as a "temporary visitor," you are very likely to be required to have a return ticket (not that you are required to show it at the entry airport every time). Is there any way you can find a reasonably priced return tickets with the return date changeable? Oftentimes return tickets can cost only as much as a one-way ticket too.

Two items (AK has it pretty well covered):
1 - To get married, visit the US embassy and get the affidavit (US50) and visit city-hall and fill out the forms. Simple, quick, easy.
2 - On the plane ticket, it is not Japan Immigration that will be the problem, it will be your airline. Without an onward ticket or resident status they can deny you boarding when you try to leave the USA. I get this when flying back to Japan after visiting family back in NZ - I simply have to prove I have resident status. So you have better check with them first (get it in writing) - on arrival in Japan my understanding is that without onward travel (I've never been asked for proof of that in ten years), you might need to show proof of funds that you are able to purchase onward travel.

As a related thought, on your immigration form you were probably thinking of declaring purpose of stay as tourist/tourism, when your intention is to get a visa/status of residence so that would be a false declaration. I don't remember the other tick boxes, but you should be careful of making false declarations on official documents.

Thank you both for your answers. I kind of spontaneously bought a one way ticket to Japan because the price was right, along with another ticket to Seoul within the 90 days of the visa, in hopes of possibly avoiding raising any red flags. I'm not sure whether it was a good idea or not, but I'm going to keep my hopes up.
With the immigration form, I believe the only other option would be "Other", do you suppose I should check that box and fill out my intentions in the blank spot provided?

I pulled a copy of the form off the web and "other" looks to be a good option.

I think (personal opinion) you have a legitimate reason to be visiting, you have a plan (including an onward ticket if required), financial resources, and are aware of your responsibilities. At worst, you should get the standard 90 day temporary visitor permit with a few questions about what you are doing during your stay.
Once in Japan, there are not any real roadblocks if you follow the procedure and you can get married and then apply for the visa/status of reidence.

As a related item, I have helped two couple get married in Japan (one from the USA and one from the UK) and both were done as part of their tourism activities while on holiday. Certainly there is nothing at immigration that stops you entering the country for the purposes of getting married - as that is almost incidental paperwork. Just like immigration don't stop people that want to do a million other things while they are in the country that are legal and permitted activities.